If you say Y here the kernel will use a 4Kb stacksize for thekernel stack attached to each process/thread. This facilitatesrunning more threads on a system and also reduces the pressureon the VM subsystem for higher order allocations. This optionwill also use IRQ stacks to compensate for the reduced stackspace.

not sure if thats what your looking for, no clue about any sysctrl or other method of changing it on the fly.